Preheat oven to 450 degrees F. In a bowl, mix together the sugars.

Heat a large oven-safe skillet over medium-high heat and add bacon, frying until crisp and fat is rendered. Once crispy, remove with kitchen tongs and place on a paper towel to drain. Pour most of the bacon grease out of the skillet and into an heat-safe jar, leaving just a thin layer in the skillet. Reduce heat to medium-low.

Sprinkle the cut-side up of peaches with half of the sugar mixture, the salt and the pepper. Place them cut-side done in the skillet, tucking the rosemary in between. Cook for 5 minutes, or until cut sides are caramely and golden. Sprinkle the remaining sugar on the un-cut side of the peaches. Drizzle a bit of bacon grease (1-2 teaspoons) over the peaches, then place in the oven and roast for 10 minutes.

Remove from the oven and flip the peaches so they are cut-side up. Roast for another 5-10 minutes, until soft and fragrant. Remove from the oven and serve immediately, discarding rosemary, and sprinkle on the crumbled bacon and blue cheese. Serve alone or with ice cream, yogurt or salads.